The WeakMap object has key-value pair as elements where the key should be an object and the value can be any primitive value or object. The objects which are used as keys in a WeakMap are garbage collected if they don’t have any reference to them.
Following is the code for WeakMap object in JavaScript −
Example
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <style> body { font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif; } .result { font-size: 18px; font-weight: 500; color: rebeccapurple; } </style> </head> <body> <h1>WeakMap object in JavaScript</h1> <div class="result"></div> <button class="Btn">Show WeakMap</button> <h3>Click on the above button to create and display a WeakMap object</h3> <button class="Btn">REMOVE</button> <h3>Click on the above button to remove reference of the WeakMap key</h3> <script> let resultEle = document.querySelector(".result"); let btnEle = document.querySelectorAll(".Btn"); let personObj = { name: "Rohan Sharma", age: 22, class: 9, }; let WeakMap1 = new WeakMap(); WeakMap1.set(personObj, "Rohan Object"); btnEle[0].addEventListener("click", () => { resultEle.innerHTML = "personObj : " + WeakMap1.get(personObj) + "<br>"; }); btnEle[1].addEventListener("click", () => { personObj = null; resultEle.innerHTML += "personObj : " + WeakMap1.get(personObj) + "<br>"; resultEle.innerHTML += " personObj is now removed from memory"; }); </script> </body> </html>
Output
The above code will produce the following output −
On clicking the ‘Show WeakMap’ button −
On clicking the ‘REMOVE’ button −